1987 Sharnoa SDC-80D Z axis out of position

[ERIC14779]

We have an old 1987 Sharnoa SDC-80D with a Tiger 6 control in our shop. We are using it daily again for a project. (It sits sometimes for months) and the operator states that the spindle seems to slowly NOT come all the way up to toolchange position ( a little lower and lower over time). And he has to re-home to get it back. and it does it again over time. He says he has to re reference the machine 2 to 3 times in 10 hrs. of running.

 

I have no experience with these Tiger controls and Sharnoa Servo systems, Can anybody point me in the right direction, and what to check ??

[ERIC14779]

UPDATE....

 

Got a email back from a Sharnoa service tech... he agrees that the machine is loosing encoder counts somewhere... (Yea no kidding)

 

now I have to find where.... anybody have experience tracking down this type of problem... I know to check wiring, connectors etc. is there a place that is more prone to a problem than any other on this machine ???

[ERIC14779]

UPDATE 3/10/11

 

Well I replaced the entire Z axis Encoder Cable, the old one was not shielded and the compliment signals were not being used.

 

there was a box that all 3 axis encoder cables ran into the had a inverse converter that recreated the compliment signals from the primary ones, then the result was feed into the motion control board...

 

 

WTF !!!! but that is the was it was... Now the Z axis signals (all) from the encoder are feed directly into the motion card..... So far So good...

 

 

B)B)B)